Redundancy-Based Validity Screening of Strain-Gauge Records from In-Service Hydraulic Turbine Servomotors

Strain gauges on the push–pull rod are a practical means of measuring the load on in-service hydraulic actuators, but the channels degrade silently, and a degraded channel still yields a credible-looking load characteristic. A redundancy-based validity screen for such records is presented and applied to every record from four guide-vane servomotors of Francis units under wind–photovoltaic–hydro complementary dispatch. Four elementary screens are combined: channel coherence with an applicability floor, configuration sensitivity of the interval loading gradient against a tolerance band built from fifteen reference channel configurations, step magnitude, and abscissa integrity. The screen refuses none of the reference configurations, in sample or under leave-one-out. At a three-channel actuator it localises a disagreement to one gauge; at a two-channel actuator it can only detect one, and it refuses a record whose loading gradient, −310 kN per unit relative opening, lies 365 kN below the reference range. For records that pass, loop energy is expressed through a stroke-free dissipation index and a growth rate. The channel configuration carried forward at a single actuator moves the cross-actuator coefficient of variation in the index between 6.6% and 20.8%, whereas the grouping by growth rate is preserved for every configuration that excludes the isolated gauge.